Back pain, and particularly lower back pain, is a common disabling problem of the body. In the back or posterior end of the body, the epidural space is located in and extending the length of the spine. The epidural space contains fat, connective tissue, blood vessels, lymphatic vessels, nerve fibers, as well as other structures. FIGS. 9a and 9b illustrate, the crescent shaped cross-section of the epidural space 110 and its position within the spinal column 118. The epidural space 110 is defined along the edge (or side) by dura mater 112 that surrounds spinal cord 118. The epidural space is further defined along a second edge (or side) by the periosteum of the bony vertebrae or by ligamentum-flavum 114 at the vertebral interspaces. Along the interior surface of the periosteum or ligamentum-flavum 114 lies venus plexis 119, a complex configuration of veins. Web-like fibrosis 120 may adhere to dura mater 112 and the periosteum and/or the ligamentum-flavum 114. These fibrosis may be formed in a random manner or in layers that form lesions extending across epidural space 110 or parallel thereto.
The various lesions, as well as cystical masses and nerve damage, which occur in and around the epidural space can cause various back problems for the human body. Fibrosis often comprise an epidural lesion, which may have a consistency ranging from very soft to tougher, scar-tissue.
An epidural lesion may extend through the epidural space over the length of two or three vertebrae and are believed to be a source of lower back pain and possibly sciatica in human beings. These lesions are believed to be caused by postoperative scarring of nerves, particularly from laminectomy procedures. A ruptured disc or a leaking disc, caused by an annular tear, also are believed to be a cause. Adhesions are often attached to the nerve roots or sleeves themselves causing compression and/or tethering of these neural elements, causing intractable pain and disability. This condition is often related to post surgical changes related to inflammation or bleeding in the epidural spaces resulting in scar tissue formation with resultant contraction over time. Many other conditions can contribute to the above affliction in the epidural space, including leakage of material from the compromised inter-vertebral disc, infection, tumor, and a number of other medical conditions. The result of these afflictions is loss of the epidural space and/or inflammation in the same space. These lesions generally have their greatest negative effect when they exist in the anterior lateral epidural space.
Epidural lesions and other epidural afflictions have been treated by numerous methods. One known method is surgical exploration. Unfortunately, surgical exploration is difficult, time-consuming and often results in a painful post-operative recovery.
Epidural afflictions have also been investigated and treated through the methods and devices disclosed in U.S. Pat. No. 5,232,442, the disclosure of which is incorporated herein by reference. Epidural lesions also have been treated by fluid lysis. In fluid lysis, an epidural catheter often comprising a flexible tubular shaft having an open distal end is introduced between the vertebrae of the spinal column and into the epidural space. The distal end of the epidural catheter is positioned adjacent the fibrosis comprising the lesion. A desired volume of fluid is then delivered through the catheter and directed against the fibrosis with enough force to break the web-like layers comprising the lesion. Unfortunately, fluid lysis can be ineffective because the fluid takes the path of least resistance upon leaving the distal end of the catheter and fails to impact the fibrosis with enough force to destroy the lesion. Consequently the lesion is not removed and the procedure must be repeated.
Fluoroscopic observation techniques have also been used to investigate and treat various sources of problems associated with back pain. See, for example, U.S. Pat. No. 5,215,105, the disclosure of which is incorporated herein by reference. These fluoroscopic techniques help guide devices, but fail to give a detailed picture of structures within vessels or cavities, such as the epidural space, and therefore are limited in their ability to identify the source of back pain. For example, fiber optic scopes (or fiberscopes) have been used for various types of surgery. These fiberscopes often are inserted into a vein or an artery for viewing blockage or the like within the vein or artery. The epidural space, however, has not fully been explored using visual techniques because the epidural space, as described above, does not take the form of a vein or artery. Instead, the epidural space collapses around an instrument or device inserted therein.
Endoscopes have been used to investigate and treat internal areas or organs within a body vessel or cavity, such as the epidural space. An elongated insertable part of the endoscope is inserted through a tube or sleeve that is itself inserted into a body vessel or cavity, or directly into the body vessel or cavity itself. See, for example, U.S. Pat. No. 5,195,541, the disclosure of which is incorporated herein by reference. These endoscopes, however, are relatively large with respect to a catheter and, therefore, difficult and dangerous to operate.
Practitioners have also used contrast injections under fluoroscopy to investigate and treat epidural afflictions. More recently, epidurography and/or epiduroscopy has improved diagnosis and treatment. Equipment and technology have only recently allowed epidurography to diagnose and treat these most difficult and incapacitating medical conditions. Because the epidural space is continuous with the dura and the neuro-foramina, it is the obvious starting cavity to diagnose and treat many of the epidural afflictions.
Therefore, there is still a need for a device for and a method of epidural exploration and surgery that allows a physician or use to effectively enter the epidural space, visually observe a problem area, and therapeutically treat the problem area in or around the epidural space in a minimal amount of time and with minimal amount of damage.